In producing devices by combining very fine thin film patterns such as semiconductor devices and liquid crystal display devices, this invention relates to a measuring/monitoring apparatus for measuring a film formation condition and a processing condition in a film formation processing for forming a thin film, a planarization processing for planarizing the resulting thin film, an etching processing for forming very fine patterns on the thin film, etc, a film thickness/etching depth measuring apparatus having the measuring/monitoring apparatus assembled therein, a measuring/monitoring method using these apparatuses, and a film formation/processing method.
In a film formation processing, a planarization processing and a very fine pattern formation processing that are employed for producing semiconductor devices or liquid crystal display devices, it is very important to precisely determine a change of a film thickness and a condition of progress of the very fine pattern formation processing, and to execute a series of processing as designed originally. An interference method that utilizes interference of light has been broadly used to measure a film thickness and a progress condition of a very fine pattern processing during these processing. JP-A-8-292012, for example, describes an etching end point detector that detects the end point of the very fine pattern formation by utilizing interference as a prior art technology.
JP-A-11-153416 discloses a method of measuring a thickness of a film formed on a substrate by interference. Also, JP-A-7-4921 discloses a method of measuring a film thickness in a planarization processing of a substrate surface. This reference describes measurement of a film thickness during polishing of a semiconductor wafer by the steps of irradiating measuring light having a wavelength that transmits through the substrate during the film thickness measurement, and measuring the thickness of a thin film on the basis of reflected light of measuring light that is reflected after transmitting through the substrate. Further, JP-A-10-111186 teaches to improve accuracy of temperature measurement by radiated infrared light by using a filter.
However, these prior art technologies are not yet free from the following problems. The etching end point detector disclosed in JP-A-8-292012 measures a surface condition of a processed substrate through a processing chamber. Since the condition inside the processing chamber and the condition of an inner wall surface of an inspection window for inspection change in the course of repetition of the processing, and this change affects the measurement result. In consequence, high precision measurement and monitoring are difficult.
The method of measuring the processing condition of the surface of the processed substrate from its back as described in JP-A-11-153416 and JP-A-7-4921 cannot easily detect with high accuracy reflected light from the substrate surface for measuring the condition of the substrate surface because the influences of reflected light from the substrate surface are great.
It is an object of the present invention to provide a measuring/monitoring apparatus capable of selectively detecting reflected light from a substrate surface for measuring the condition of the substrate surface, and capable of precisely measuring the condition of the substrate surface in order to measure a film thickness or an etching depth without influences of a processing condition and an internal condition of a processing chamber.
It is another object of the present invention to provide a film formation/etching measuring apparatus having a high precision measuring/monitoring apparatus of a substrate surface assembled therein, and a high precision film formation method by using such measuring/monitoring apparatuses. The present invention aims at accomplishing either of these objects.
To accomplish the objects described above, a first feature of the present invention resides in a measuring apparatus comprising irradiation means for irradiating measuring light from the back of a substrate in such a fashion that measuring light can be totally reflected from both first and second surfaces formed on the surface side of the substrate, and measurement means for causing reflected lights of measuring light irradiated by the irradiation means and reflected from the first and second surfaces to interfere with each other, and thus measuring a distance between the first and second surfaces.
A second feature of the present invention for accomplishing the objects described above resides in a measuring apparatus for measuring a film thickness of a film formed on a surface of a substrate or a depth of a processed surface processed on a substrate surface by optical interference means, comprising irradiation means capable of irradiating measuring light from the back of the substrate in such a fashion that measuring light is totally reflected from both an interface between a film formed on the substrate surface and the substrate and a processed surface of the substrate or a film surface, and measurement means for measuring a film thickness or a processing depth by causing reflected light from the interface and reflected light from the processing surface or the film surface to interfere with each other.
A third feature of the present invention for accomplishing the objects described above resides in a measuring apparatus for measuring a film thickness of a film formed on a surface of a substrate or a depth of a processed surface processed on a substrate surface by optical interference means, comprising irradiation means capable of irradiating measuring light from the back of the substrate in such a fashion that measuring light is totally reflected from both an interface between a film formed on the substrate surface and the substrate, and a processed surface of the substrate or a film surface, and measurement means for measuring a film thickness or a processing depth by causing reflected light from the interface and reflected light from the processing surface or the film surface to interfere with each other, wherein the irradiation means can irradiate irradiation light at different angles of incidence to the back of the substrate and can vary the angle of incidence of irradiation light so that an optical path difference of irradiation light transmitting through the substrate is greater than the wavelength of incident light, and an optical path difference due to the film thickness of the film or the processing depth as an object of measure is smaller than the wavelength of incident light.
A fourth feature of the present invention for accomplishing the objects described above resides in a measuring apparatus for measuring a film thickness of a film formed on a substrate surface by optical interference means, comprising means for irradiating from the back of the substrate both measuring light under a condition where measuring light is totally reflected on the surface of the film formed on the substrate surface, and measuring light under a condition where measuring light is totally reflected by an interface between the film and the substrate, and means for measuring the film thickness by causing reflected light from the surface of the film and reflected light from the interface between the film and the substrate to interfere with each other, and thus measuring the film thickness.
In each of the features described above, the irradiation means can irradiate measuring length having a plurality of measuring light, and the measurement means preferably measures the film thickness or the processing depth from the interference result for each wavelength.
A fifth feature of the present invention for accomplishing the objects described above resides in a thin film formation apparatus for forming a thin film on a substrate, comprising irradiation means for irradiating, from a back of a substrate, measuring light in such a fashion that measuring light is totally reflected by an interface between a film formed on a substrate surface and the substrate, measurement means for measuring a film thickness by causing reflected light from the interface and reflected light from a surface of the film to interfere with each other, and thus measuring the film thickness, and means for forming a thin film on the substrate by feeding back the film thickness measured by the measurement means.
A sixth feature of the present invention for accomplishing the objects described above resides in a processing apparatus of a substrate surface, comprising means for irradiating measuring light from a back of a substrate in such a fashion that measuring light is totally reflected from both substrate surface and processed surface of the substrate means for measuring a processing depth by causing reflected light from the substrate surface and reflected light from the processing surface to interfere with each other, and means for processing the substrate surface on the basis of the processing depth measured by the means for measuring the processing depth.
A seventh feature of the present invention for accomplishing the objects described above resides in a method of forming a thin film, comprising the steps of irradiating measuring light from a back of a substrate in such a fashion that measuring light is totally reflected from an interface between a film formed on a substrate surface and the substrate, causing reflected light from the interface and reflected light from the surface of the film to interfere with each other and thus measuring the film thickness, calculating a difference between the film thickness so measured and a target value of a film thickness set in advance, and controlling a processing condition of film formation on the basis of the difference.
An eighth feature of the present invention resides in a method of processing a substrate surface, comprising the steps of irradiating from a back of a substrate measuring light in such a fashion that reflecting light is totally reflected from both substrate surface and a processing surface formed on the same side as the substrate surface, causing reflected light from the substrate surface and reflected light from the processing surface to interfere with each other, and thus measuring a processing depth, calculating a difference between a processing depth so measured and a target value of a processing depth set in advance, and controlling a processing condition of the substrate surface on the basis of the difference.
A ninth feature of the present invention resides in an apparatus for measuring a temperature, including measurement means for measuring an intensity of infrared light irradiated, and measuring the intensity of infrared light radiated from the substrate to measure a temperature of the substrate, wherein the measurement range of infrared light by the measurement means for measuring the intensity of radiated infrared light is set to a region outside an optical path region through which radiated infrared light generated from a radiated infrared light generation range other than the substrate as a measurement object passes.
Owing to these features, the present invention can expel reaction products, whose adhesion amounts increase with repetition of processing, from the measurement region even when the change of the condition inside the processing chamber and the change of the condition of the inner wall surface of an inspection window for observation adversely affect the measurement result, and therefore can execute measurement and monitoring with high reproducibility. Measurement from the back of the substrate is conducted under the condition of the angle of incidence at which measuring light irradiated to the back is totally reflected on the substrate surface. In consequence, the intensity of reflected light from the back of the substrate can be improved, and measurement and monitoring can be conducted highly precisely. Further, the angle of incidence of measuring light irradiated to the back of the substrate is furnished with expansion, so that interference between reflected light from the back of the substrate and reflected light from the substrate surface can be reduced. Thus, the change of the interference intensity of reflected light from the back of the substrate can be measured and monitored highly precisely.
When the film thickness is measured, the expansion of the angle of incidence is controlled so as to control the proportion of reflected light from the film surface to reflected light from the interface between the film and the substrate, to thus optimize the interference intensity of reflected light and to conduct precise measurement and monitoring.
A detection mechanism for detecting infrared light radiated from the processing substrate is disposed in a region through which plasma and infrared ray radiated from the inner wall surface of the processing chamber do not optically transmit. Accordingly, measurement and monitoring can be precisely conducted. In film formation-, processing- and etching apparatuses having the measuring/monitoring apparatus assembled therein, the measuring/monitoring apparatuses for measuring from the back of the substrate are buried into a stage for placing the substrate so that a processing distribution of the substrate and its processing condition can be measured and monitored. The processing conditions are controlled on the basis of these results so that an optimum processing can be made.